#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
#define fi first
#define se second
#define vi vector<int>
#define vll vector<long long>
#define pii pair<int, int>
#define pll pair<long long, long long>
#define pb push_back
#define mp make_pair
#define eb emplace_back
#define all(x) (x).begin(), (x).end()
#define sz(x) (int)(x).size()
mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
mt19937_64 rng64(chrono::high_resolution_clock::now().time_since_epoch().count());
inline int rand(int l,int r){return uniform_int_distribution<int>(l, r)(rng);}
inline ll rand(ll l,ll r){return uniform_int_distribution<ll>(l, r)(rng64);}
#ifdef DEBUG
auto&operator<<(auto&o,pair<auto,auto>p){return o<<"("<<p.first<<", "<<p.second<<")";}
auto operator<<(auto&o,auto x)->decltype(x.end(),o){o<<"{";int i=0;for(auto e:x)o<<","+!i++<<e;return o<<"}";}
#define debug(X...)cerr<<"["#X"]: ",[](auto...$){((cerr<<$<<"; "),...)<<endl;}(X)
#else
#define debug(...){}
#endif
struct custom_hash {
static uint64_t splitmix64(uint64_t x) {
x += 0x9e3779b97f4a7c15;
x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
return x ^ (x >> 31);
}
size_t operator()(uint64_t x) const {
static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
return splitmix64(x + FIXED_RANDOM);
}
};
struct pair_hash{
size_t operator()(const pair<int,int>&x)const{
return hash<long long>()(((long long)x.first)^(((long long)x.second)<<32));
}
};
const int MAXN = 1e5 + 7;
int n, m;
vi a;
set<pii> b;
vi B;
string ans = "";
pii dp[MAXN][(1 << 3)];
int pre[MAXN][(1 << 3)];
bool inside(int x, int msk, int K, int ind){
for(int j = ind; j <= ind + 2; j++){
if((1 << (j - ind)) & msk){
if(B[x] >= a[j] && B[x] <= a[j] + K){
return true;
}
}else{
if(B[x] <= a[j] && B[x] >= a[j] - K){
return true;
}
}
}
return false;
}
bool check(int K){
//b - kwiatki
for(int msk = 0; msk < (1 << 3); msk++){
int wsk = 0;
while(wsk < sz(B) && inside(wsk, msk, K, 0)){
wsk++;
}
dp[2][msk] = mp(-1, -1);
for(int j = 0; j < 3; j++){
if((1 << j) & msk){
dp[2][msk].se = max(dp[2][msk].se, a[j] + K);
}else{
dp[2][msk].se = max(dp[2][msk].se, a[j]);
}
}
dp[2][msk].fi = wsk;
}
for(int i = 3; i < n; i++){
for(int msk = 0; msk < (1 << 3); msk++){
for(int prevAdd = 0; prevAdd < 2; prevAdd++){
int prevMsk = msk / 2 + (1 << 2) * prevAdd;
if(dp[i - 1][prevMsk].fi < sz(B) && B[dp[i - 1][prevMsk].fi] < a[i] - K){
dp[i][msk].fi = dp[i - 1][prevMsk].fi;
continue;
}
if(msk & 1){
//i-ty w prawo
dp[i][msk].se = max(dp[i - 1][prevMsk].se, a[i] + K);
if(dp[i - 1][prevMsk].fi < sz(B) && B[dp[i - 1][prevMsk].fi] >= a[i]){
auto it = b.upper_bound(mp(dp[i][msk].se, 0));
if(it == b.end()){
dp[i][msk].fi = sz(B);
}else{
dp[i][msk].fi = (*it).se;
}
}else{
dp[i][msk].fi = dp[i - 1][prevMsk].fi;
}
}else{
//i-ty w lewo
dp[i][msk].se = max(dp[i - 1][prevMsk].se, a[i]);
if(dp[i - 1][prevMsk].fi < sz(B)){
auto it = b.upper_bound(mp(dp[i][msk].se, 0));
if(it == b.end()){
dp[i][msk].fi = sz(B);
}else{
dp[i][msk].fi = (*it).se;
}
}else{
dp[i][msk].fi = dp[i - 1][prevMsk].fi;
}
}
}
}
}
for(int msk = 0; msk < (1 << 3); msk++){
if(dp[n - 1][msk].fi == sz(B)){
ans = "";
int ind = n - 1;
int curr = msk;
while(ind > 2){
if(curr & 1){
ans += "R";
}else{
ans += "L";
}
curr = pre[ind][curr];
ind--;
}
while(ind >= 0){
if(curr & 1){
ans += "R";
}else{
ans += "L";
}
ind--;
curr /= 2;
}
reverse(all(ans));
return true;
}
}
return false;
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(NULL);
cout.tie(NULL);
cin >> n >> m;
a.resize(n);
for(int i = 0; i < n; i++){
cin >> a[i];
}
while(sz(a) < 3){
a.pb((int)2e9 + 7);
n++;
}
B = {};
for(int i = 0; i < m; i++){
int x;
cin >> x;
B.pb(x);
b.insert(mp(x, i));
}
int l = 0;
int p = (int)1e9;
int mid;
while(l < p){
mid = (l + p) / 2;
if(check(mid)){
p = mid;
}else{
l = mid + 1;
}
}
if(!check(l)){
cout << "-1\n";
return 0;
}
cout << l << '\n';
cout << ans << '\n';
return 0;
}
